This invention relates to thermal storage and particularly to storage of heat in reaction by-products of intermittent processes.
The preferred embodiment relates to a vehicle having an engine which derives power from a reaction of an alkali metal with water in the presence of air which reaction forms hot alkali hydroxides as disclosed in my U.S. Pat. No. 4,020,798. The alkali metal and water reactants are subject to freezing in frigid weather. The freezing temperature of water could be lowered well below the -12.3.degree. C. freezing temperature of the eutectic alloy of sodium and potassium, called NaK, by addition of an alcohol which would burn when ignited in the engine. Similarly, the freezing temperature of NaK could be lowered by alloying with cesium down to the -72.degree. C. freezing temperature of the ternary eutectic alloy. Addition of alcohol and cesium, however, would add to system complexity and cost and it is preferable to provide means to retard freezing and to thaw the reactants should freezing occur. Such thawing means could also provide other heating functions such as warming the vehicle's interior.